The present invention relates to an oxidative hair dye composition containing an alkaline agent and an oxidant.
In general, as a hair cosmetic composition, there has been known a hair dye exhibiting effects by mixing a plurality of chemicals. As such a hair cosmetic composition, for example, there has been known an oxidative hair dye composed of a first agent containing an alkaline agent and an oxidative dye, and a second agent containing an oxidant such as hydrogen peroxide. The alkaline agent promotes the action of the oxidant contained in the second agent, and also improves the hair-dyeing power by swelling hair so as to improve the permeability of the dye into the hair. The oxidative dye is a compound capable of developing a color due to the oxidation polymerization caused by the oxidant contained in the second agent, and is classified into a dye intermediate and a coupler. Various types of couplers have hitherto been known; for example, Japanese Laid-Open Patent Publication No. 2008-94820 discloses an oxidative hair dye containing α-naphthol as a coupler and formulated as a cream.